1 /* Handle SVR4 shared libraries for GDB, the GNU Debugger.
3 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,
4 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
5 Free Software Foundation, Inc.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "elf/external.h"
25 #include "elf/common.h"
36 #include "gdbthread.h"
39 #include "gdb_assert.h"
43 #include "solib-svr4.h"
45 #include "bfd-target.h"
49 #include "exceptions.h"
51 static struct link_map_offsets
*svr4_fetch_link_map_offsets (void);
52 static int svr4_have_link_map_offsets (void);
53 static void svr4_relocate_main_executable (void);
55 /* Link map info to include in an allocated so_list entry */
59 /* Pointer to copy of link map from inferior. The type is char *
60 rather than void *, so that we may use byte offsets to find the
61 various fields without the need for a cast. */
64 /* Amount by which addresses in the binary should be relocated to
65 match the inferior. This could most often be taken directly
66 from lm, but when prelinking is involved and the prelink base
67 address changes, we may need a different offset, we want to
68 warn about the difference and compute it only once. */
71 /* The target location of lm. */
75 /* On SVR4 systems, a list of symbols in the dynamic linker where
76 GDB can try to place a breakpoint to monitor shared library
79 If none of these symbols are found, or other errors occur, then
80 SVR4 systems will fall back to using a symbol as the "startup
81 mapping complete" breakpoint address. */
83 static char *solib_break_names
[] =
89 "__dl_rtld_db_dlactivity",
95 static char *bkpt_names
[] =
103 static char *main_name_list
[] =
109 /* Return non-zero if GDB_SO_NAME and INFERIOR_SO_NAME represent
110 the same shared library. */
113 svr4_same_1 (const char *gdb_so_name
, const char *inferior_so_name
)
115 if (strcmp (gdb_so_name
, inferior_so_name
) == 0)
118 /* On Solaris, when starting inferior we think that dynamic linker is
119 /usr/lib/ld.so.1, but later on, the table of loaded shared libraries
120 contains /lib/ld.so.1. Sometimes one file is a link to another, but
121 sometimes they have identical content, but are not linked to each
122 other. We don't restrict this check for Solaris, but the chances
123 of running into this situation elsewhere are very low. */
124 if (strcmp (gdb_so_name
, "/usr/lib/ld.so.1") == 0
125 && strcmp (inferior_so_name
, "/lib/ld.so.1") == 0)
128 /* Similarly, we observed the same issue with sparc64, but with
129 different locations. */
130 if (strcmp (gdb_so_name
, "/usr/lib/sparcv9/ld.so.1") == 0
131 && strcmp (inferior_so_name
, "/lib/sparcv9/ld.so.1") == 0)
138 svr4_same (struct so_list
*gdb
, struct so_list
*inferior
)
140 return (svr4_same_1 (gdb
->so_original_name
, inferior
->so_original_name
));
143 /* link map access functions */
146 LM_ADDR_FROM_LINK_MAP (struct so_list
*so
)
148 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
149 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
151 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_addr_offset
,
156 HAS_LM_DYNAMIC_FROM_LINK_MAP (void)
158 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
160 return lmo
->l_ld_offset
>= 0;
164 LM_DYNAMIC_FROM_LINK_MAP (struct so_list
*so
)
166 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
167 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
169 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_ld_offset
,
174 LM_ADDR_CHECK (struct so_list
*so
, bfd
*abfd
)
176 if (so
->lm_info
->l_addr
== (CORE_ADDR
)-1)
178 struct bfd_section
*dyninfo_sect
;
179 CORE_ADDR l_addr
, l_dynaddr
, dynaddr
;
181 l_addr
= LM_ADDR_FROM_LINK_MAP (so
);
183 if (! abfd
|| ! HAS_LM_DYNAMIC_FROM_LINK_MAP ())
186 l_dynaddr
= LM_DYNAMIC_FROM_LINK_MAP (so
);
188 dyninfo_sect
= bfd_get_section_by_name (abfd
, ".dynamic");
189 if (dyninfo_sect
== NULL
)
192 dynaddr
= bfd_section_vma (abfd
, dyninfo_sect
);
194 if (dynaddr
+ l_addr
!= l_dynaddr
)
196 CORE_ADDR align
= 0x1000;
197 CORE_ADDR minpagesize
= align
;
199 if (bfd_get_flavour (abfd
) == bfd_target_elf_flavour
)
201 Elf_Internal_Ehdr
*ehdr
= elf_tdata (abfd
)->elf_header
;
202 Elf_Internal_Phdr
*phdr
= elf_tdata (abfd
)->phdr
;
207 for (i
= 0; i
< ehdr
->e_phnum
; i
++)
208 if (phdr
[i
].p_type
== PT_LOAD
&& phdr
[i
].p_align
> align
)
209 align
= phdr
[i
].p_align
;
211 minpagesize
= get_elf_backend_data (abfd
)->minpagesize
;
214 /* Turn it into a mask. */
217 /* If the changes match the alignment requirements, we
218 assume we're using a core file that was generated by the
219 same binary, just prelinked with a different base offset.
220 If it doesn't match, we may have a different binary, the
221 same binary with the dynamic table loaded at an unrelated
222 location, or anything, really. To avoid regressions,
223 don't adjust the base offset in the latter case, although
224 odds are that, if things really changed, debugging won't
227 One could expect more the condition
228 ((l_addr & align) == 0 && ((l_dynaddr - dynaddr) & align) == 0)
229 but the one below is relaxed for PPC. The PPC kernel supports
230 either 4k or 64k page sizes. To be prepared for 64k pages,
231 PPC ELF files are built using an alignment requirement of 64k.
232 However, when running on a kernel supporting 4k pages, the memory
233 mapping of the library may not actually happen on a 64k boundary!
235 (In the usual case where (l_addr & align) == 0, this check is
236 equivalent to the possibly expected check above.)
238 Even on PPC it must be zero-aligned at least for MINPAGESIZE. */
240 if ((l_addr
& (minpagesize
- 1)) == 0
241 && (l_addr
& align
) == ((l_dynaddr
- dynaddr
) & align
))
243 l_addr
= l_dynaddr
- dynaddr
;
247 warning (_(".dynamic section for \"%s\" "
248 "is not at the expected address"), so
->so_name
);
249 warning (_("difference appears to be caused by prelink, "
250 "adjusting expectations"));
254 warning (_(".dynamic section for \"%s\" "
255 "is not at the expected address "
256 "(wrong library or version mismatch?)"), so
->so_name
);
260 so
->lm_info
->l_addr
= l_addr
;
263 return so
->lm_info
->l_addr
;
267 LM_NEXT (struct so_list
*so
)
269 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
270 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
272 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_next_offset
,
277 LM_NAME (struct so_list
*so
)
279 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
280 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
282 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_name_offset
,
287 IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list
*so
)
289 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
290 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
292 /* Assume that everything is a library if the dynamic loader was loaded
293 late by a static executable. */
294 if (exec_bfd
&& bfd_get_section_by_name (exec_bfd
, ".dynamic") == NULL
)
297 return extract_typed_address (so
->lm_info
->lm
+ lmo
->l_prev_offset
,
301 /* Per pspace SVR4 specific data. */
305 CORE_ADDR debug_base
; /* Base of dynamic linker structures */
307 /* Validity flag for debug_loader_offset. */
308 int debug_loader_offset_p
;
310 /* Load address for the dynamic linker, inferred. */
311 CORE_ADDR debug_loader_offset
;
313 /* Name of the dynamic linker, valid if debug_loader_offset_p. */
314 char *debug_loader_name
;
316 /* Load map address for the main executable. */
317 CORE_ADDR main_lm_addr
;
319 CORE_ADDR interp_text_sect_low
;
320 CORE_ADDR interp_text_sect_high
;
321 CORE_ADDR interp_plt_sect_low
;
322 CORE_ADDR interp_plt_sect_high
;
325 /* Per-program-space data key. */
326 static const struct program_space_data
*solib_svr4_pspace_data
;
329 svr4_pspace_data_cleanup (struct program_space
*pspace
, void *arg
)
331 struct svr4_info
*info
;
333 info
= program_space_data (pspace
, solib_svr4_pspace_data
);
337 /* Get the current svr4 data. If none is found yet, add it now. This
338 function always returns a valid object. */
340 static struct svr4_info
*
343 struct svr4_info
*info
;
345 info
= program_space_data (current_program_space
, solib_svr4_pspace_data
);
349 info
= XZALLOC (struct svr4_info
);
350 set_program_space_data (current_program_space
, solib_svr4_pspace_data
, info
);
354 /* Local function prototypes */
356 static int match_main (char *);
358 static CORE_ADDR
bfd_lookup_symbol (bfd
*, char *);
364 bfd_lookup_symbol -- lookup the value for a specific symbol
368 CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
372 An expensive way to lookup the value of a single symbol for
373 bfd's that are only temporary anyway. This is used by the
374 shared library support to find the address of the debugger
375 notification routine in the shared library.
377 The returned symbol may be in a code or data section; functions
378 will normally be in a code section, but may be in a data section
379 if this architecture uses function descriptors.
381 Note that 0 is specifically allowed as an error return (no
386 bfd_lookup_symbol (bfd
*abfd
, char *symname
)
390 asymbol
**symbol_table
;
391 unsigned int number_of_symbols
;
393 struct cleanup
*back_to
;
394 CORE_ADDR symaddr
= 0;
396 storage_needed
= bfd_get_symtab_upper_bound (abfd
);
398 if (storage_needed
> 0)
400 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
401 back_to
= make_cleanup (xfree
, symbol_table
);
402 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
404 for (i
= 0; i
< number_of_symbols
; i
++)
406 sym
= *symbol_table
++;
407 if (strcmp (sym
->name
, symname
) == 0
408 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
410 /* BFD symbols are section relative. */
411 symaddr
= sym
->value
+ sym
->section
->vma
;
415 do_cleanups (back_to
);
421 /* On FreeBSD, the dynamic linker is stripped by default. So we'll
422 have to check the dynamic string table too. */
424 storage_needed
= bfd_get_dynamic_symtab_upper_bound (abfd
);
426 if (storage_needed
> 0)
428 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
429 back_to
= make_cleanup (xfree
, symbol_table
);
430 number_of_symbols
= bfd_canonicalize_dynamic_symtab (abfd
, symbol_table
);
432 for (i
= 0; i
< number_of_symbols
; i
++)
434 sym
= *symbol_table
++;
436 if (strcmp (sym
->name
, symname
) == 0
437 && (sym
->section
->flags
& (SEC_CODE
| SEC_DATA
)) != 0)
439 /* BFD symbols are section relative. */
440 symaddr
= sym
->value
+ sym
->section
->vma
;
444 do_cleanups (back_to
);
451 /* Read program header TYPE from inferior memory. The header is found
452 by scanning the OS auxillary vector.
454 If TYPE == -1, return the program headers instead of the contents of
457 Return a pointer to allocated memory holding the program header contents,
458 or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
459 size of those contents is returned to P_SECT_SIZE. Likewise, the target
460 architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE. */
463 read_program_header (int type
, int *p_sect_size
, int *p_arch_size
)
465 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
466 CORE_ADDR at_phdr
, at_phent
, at_phnum
;
467 int arch_size
, sect_size
;
471 /* Get required auxv elements from target. */
472 if (target_auxv_search (¤t_target
, AT_PHDR
, &at_phdr
) <= 0)
474 if (target_auxv_search (¤t_target
, AT_PHENT
, &at_phent
) <= 0)
476 if (target_auxv_search (¤t_target
, AT_PHNUM
, &at_phnum
) <= 0)
478 if (!at_phdr
|| !at_phnum
)
481 /* Determine ELF architecture type. */
482 if (at_phent
== sizeof (Elf32_External_Phdr
))
484 else if (at_phent
== sizeof (Elf64_External_Phdr
))
489 /* Find the requested segment. */
493 sect_size
= at_phent
* at_phnum
;
495 else if (arch_size
== 32)
497 Elf32_External_Phdr phdr
;
500 /* Search for requested PHDR. */
501 for (i
= 0; i
< at_phnum
; i
++)
503 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
504 (gdb_byte
*)&phdr
, sizeof (phdr
)))
507 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
508 4, byte_order
) == type
)
515 /* Retrieve address and size. */
516 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
518 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
523 Elf64_External_Phdr phdr
;
526 /* Search for requested PHDR. */
527 for (i
= 0; i
< at_phnum
; i
++)
529 if (target_read_memory (at_phdr
+ i
* sizeof (phdr
),
530 (gdb_byte
*)&phdr
, sizeof (phdr
)))
533 if (extract_unsigned_integer ((gdb_byte
*)phdr
.p_type
,
534 4, byte_order
) == type
)
541 /* Retrieve address and size. */
542 sect_addr
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_vaddr
,
544 sect_size
= extract_unsigned_integer ((gdb_byte
*)phdr
.p_memsz
,
548 /* Read in requested program header. */
549 buf
= xmalloc (sect_size
);
550 if (target_read_memory (sect_addr
, buf
, sect_size
))
557 *p_arch_size
= arch_size
;
559 *p_sect_size
= sect_size
;
565 /* Return program interpreter string. */
567 find_program_interpreter (void)
569 gdb_byte
*buf
= NULL
;
571 /* If we have an exec_bfd, use its section table. */
573 && bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
575 struct bfd_section
*interp_sect
;
577 interp_sect
= bfd_get_section_by_name (exec_bfd
, ".interp");
578 if (interp_sect
!= NULL
)
580 CORE_ADDR sect_addr
= bfd_section_vma (exec_bfd
, interp_sect
);
581 int sect_size
= bfd_section_size (exec_bfd
, interp_sect
);
583 buf
= xmalloc (sect_size
);
584 bfd_get_section_contents (exec_bfd
, interp_sect
, buf
, 0, sect_size
);
588 /* If we didn't find it, use the target auxillary vector. */
590 buf
= read_program_header (PT_INTERP
, NULL
, NULL
);
596 /* Scan for DYNTAG in .dynamic section of ABFD. If DYNTAG is found 1 is
597 returned and the corresponding PTR is set. */
600 scan_dyntag (int dyntag
, bfd
*abfd
, CORE_ADDR
*ptr
)
602 int arch_size
, step
, sect_size
;
604 CORE_ADDR dyn_ptr
, dyn_addr
;
605 gdb_byte
*bufend
, *bufstart
, *buf
;
606 Elf32_External_Dyn
*x_dynp_32
;
607 Elf64_External_Dyn
*x_dynp_64
;
608 struct bfd_section
*sect
;
609 struct target_section
*target_section
;
614 if (bfd_get_flavour (abfd
) != bfd_target_elf_flavour
)
617 arch_size
= bfd_get_arch_size (abfd
);
621 /* Find the start address of the .dynamic section. */
622 sect
= bfd_get_section_by_name (abfd
, ".dynamic");
626 for (target_section
= current_target_sections
->sections
;
627 target_section
< current_target_sections
->sections_end
;
629 if (sect
== target_section
->the_bfd_section
)
631 if (target_section
< current_target_sections
->sections_end
)
632 dyn_addr
= target_section
->addr
;
635 /* ABFD may come from OBJFILE acting only as a symbol file without being
636 loaded into the target (see add_symbol_file_command). This case is
637 such fallback to the file VMA address without the possibility of
638 having the section relocated to its actual in-memory address. */
640 dyn_addr
= bfd_section_vma (abfd
, sect
);
643 /* Read in .dynamic from the BFD. We will get the actual value
644 from memory later. */
645 sect_size
= bfd_section_size (abfd
, sect
);
646 buf
= bufstart
= alloca (sect_size
);
647 if (!bfd_get_section_contents (abfd
, sect
,
651 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
652 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
653 : sizeof (Elf64_External_Dyn
);
654 for (bufend
= buf
+ sect_size
;
660 x_dynp_32
= (Elf32_External_Dyn
*) buf
;
661 dyn_tag
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_tag
);
662 dyn_ptr
= bfd_h_get_32 (abfd
, (bfd_byte
*) x_dynp_32
->d_un
.d_ptr
);
666 x_dynp_64
= (Elf64_External_Dyn
*) buf
;
667 dyn_tag
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_tag
);
668 dyn_ptr
= bfd_h_get_64 (abfd
, (bfd_byte
*) x_dynp_64
->d_un
.d_ptr
);
670 if (dyn_tag
== DT_NULL
)
672 if (dyn_tag
== dyntag
)
674 /* If requested, try to read the runtime value of this .dynamic
678 struct type
*ptr_type
;
682 ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
683 ptr_addr
= dyn_addr
+ (buf
- bufstart
) + arch_size
/ 8;
684 if (target_read_memory (ptr_addr
, ptr_buf
, arch_size
/ 8) == 0)
685 dyn_ptr
= extract_typed_address (ptr_buf
, ptr_type
);
695 /* Scan for DYNTAG in .dynamic section of the target's main executable,
696 found by consulting the OS auxillary vector. If DYNTAG is found 1 is
697 returned and the corresponding PTR is set. */
700 scan_dyntag_auxv (int dyntag
, CORE_ADDR
*ptr
)
702 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
703 int sect_size
, arch_size
, step
;
706 gdb_byte
*bufend
, *bufstart
, *buf
;
708 /* Read in .dynamic section. */
709 buf
= bufstart
= read_program_header (PT_DYNAMIC
, §_size
, &arch_size
);
713 /* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
714 step
= (arch_size
== 32) ? sizeof (Elf32_External_Dyn
)
715 : sizeof (Elf64_External_Dyn
);
716 for (bufend
= buf
+ sect_size
;
722 Elf32_External_Dyn
*dynp
= (Elf32_External_Dyn
*) buf
;
723 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
725 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
730 Elf64_External_Dyn
*dynp
= (Elf64_External_Dyn
*) buf
;
731 dyn_tag
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_tag
,
733 dyn_ptr
= extract_unsigned_integer ((gdb_byte
*) dynp
->d_un
.d_ptr
,
736 if (dyn_tag
== DT_NULL
)
739 if (dyn_tag
== dyntag
)
758 elf_locate_base -- locate the base address of dynamic linker structs
759 for SVR4 elf targets.
763 CORE_ADDR elf_locate_base (void)
767 For SVR4 elf targets the address of the dynamic linker's runtime
768 structure is contained within the dynamic info section in the
769 executable file. The dynamic section is also mapped into the
770 inferior address space. Because the runtime loader fills in the
771 real address before starting the inferior, we have to read in the
772 dynamic info section from the inferior address space.
773 If there are any errors while trying to find the address, we
774 silently return 0, otherwise the found address is returned.
779 elf_locate_base (void)
781 struct minimal_symbol
*msymbol
;
784 /* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
785 instead of DT_DEBUG, although they sometimes contain an unused
787 if (scan_dyntag (DT_MIPS_RLD_MAP
, exec_bfd
, &dyn_ptr
)
788 || scan_dyntag_auxv (DT_MIPS_RLD_MAP
, &dyn_ptr
))
790 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
792 int pbuf_size
= TYPE_LENGTH (ptr_type
);
793 pbuf
= alloca (pbuf_size
);
794 /* DT_MIPS_RLD_MAP contains a pointer to the address
795 of the dynamic link structure. */
796 if (target_read_memory (dyn_ptr
, pbuf
, pbuf_size
))
798 return extract_typed_address (pbuf
, ptr_type
);
802 if (scan_dyntag (DT_DEBUG
, exec_bfd
, &dyn_ptr
)
803 || scan_dyntag_auxv (DT_DEBUG
, &dyn_ptr
))
806 /* This may be a static executable. Look for the symbol
807 conventionally named _r_debug, as a last resort. */
808 msymbol
= lookup_minimal_symbol ("_r_debug", NULL
, symfile_objfile
);
810 return SYMBOL_VALUE_ADDRESS (msymbol
);
812 /* DT_DEBUG entry not found. */
820 locate_base -- locate the base address of dynamic linker structs
824 CORE_ADDR locate_base (struct svr4_info *)
828 For both the SunOS and SVR4 shared library implementations, if the
829 inferior executable has been linked dynamically, there is a single
830 address somewhere in the inferior's data space which is the key to
831 locating all of the dynamic linker's runtime structures. This
832 address is the value of the debug base symbol. The job of this
833 function is to find and return that address, or to return 0 if there
834 is no such address (the executable is statically linked for example).
836 For SunOS, the job is almost trivial, since the dynamic linker and
837 all of it's structures are statically linked to the executable at
838 link time. Thus the symbol for the address we are looking for has
839 already been added to the minimal symbol table for the executable's
840 objfile at the time the symbol file's symbols were read, and all we
841 have to do is look it up there. Note that we explicitly do NOT want
842 to find the copies in the shared library.
844 The SVR4 version is a bit more complicated because the address
845 is contained somewhere in the dynamic info section. We have to go
846 to a lot more work to discover the address of the debug base symbol.
847 Because of this complexity, we cache the value we find and return that
848 value on subsequent invocations. Note there is no copy in the
849 executable symbol tables.
854 locate_base (struct svr4_info
*info
)
856 /* Check to see if we have a currently valid address, and if so, avoid
857 doing all this work again and just return the cached address. If
858 we have no cached address, try to locate it in the dynamic info
859 section for ELF executables. There's no point in doing any of this
860 though if we don't have some link map offsets to work with. */
862 if (info
->debug_base
== 0 && svr4_have_link_map_offsets ())
863 info
->debug_base
= elf_locate_base ();
864 return info
->debug_base
;
867 /* Find the first element in the inferior's dynamic link map, and
868 return its address in the inferior.
870 FIXME: Perhaps we should validate the info somehow, perhaps by
871 checking r_version for a known version number, or r_state for
875 solib_svr4_r_map (struct svr4_info
*info
)
877 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
878 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
880 volatile struct gdb_exception ex
;
882 TRY_CATCH (ex
, RETURN_MASK_ERROR
)
884 addr
= read_memory_typed_address (info
->debug_base
+ lmo
->r_map_offset
,
887 exception_print (gdb_stderr
, ex
);
891 /* Find r_brk from the inferior's debug base. */
894 solib_svr4_r_brk (struct svr4_info
*info
)
896 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
897 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
899 return read_memory_typed_address (info
->debug_base
+ lmo
->r_brk_offset
,
903 /* Find the link map for the dynamic linker (if it is not in the
904 normal list of loaded shared objects). */
907 solib_svr4_r_ldsomap (struct svr4_info
*info
)
909 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
910 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
911 enum bfd_endian byte_order
= gdbarch_byte_order (target_gdbarch
);
914 /* Check version, and return zero if `struct r_debug' doesn't have
915 the r_ldsomap member. */
917 = read_memory_unsigned_integer (info
->debug_base
+ lmo
->r_version_offset
,
918 lmo
->r_version_size
, byte_order
);
919 if (version
< 2 || lmo
->r_ldsomap_offset
== -1)
922 return read_memory_typed_address (info
->debug_base
+ lmo
->r_ldsomap_offset
,
926 /* On Solaris systems with some versions of the dynamic linker,
927 ld.so's l_name pointer points to the SONAME in the string table
928 rather than into writable memory. So that GDB can find shared
929 libraries when loading a core file generated by gcore, ensure that
930 memory areas containing the l_name string are saved in the core
934 svr4_keep_data_in_core (CORE_ADDR vaddr
, unsigned long size
)
936 struct svr4_info
*info
;
939 struct cleanup
*old_chain
;
940 struct link_map_offsets
*lmo
;
943 info
= get_svr4_info ();
945 info
->debug_base
= 0;
947 if (!info
->debug_base
)
950 ldsomap
= solib_svr4_r_ldsomap (info
);
954 lmo
= svr4_fetch_link_map_offsets ();
955 new = XZALLOC (struct so_list
);
956 old_chain
= make_cleanup (xfree
, new);
957 new->lm_info
= xmalloc (sizeof (struct lm_info
));
958 make_cleanup (xfree
, new->lm_info
);
959 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
960 new->lm_info
->lm_addr
= ldsomap
;
961 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
962 make_cleanup (xfree
, new->lm_info
->lm
);
963 read_memory (ldsomap
, new->lm_info
->lm
, lmo
->link_map_size
);
964 lm_name
= LM_NAME (new);
965 do_cleanups (old_chain
);
967 return (lm_name
>= vaddr
&& lm_name
< vaddr
+ size
);
974 open_symbol_file_object
978 void open_symbol_file_object (void *from_tty)
982 If no open symbol file, attempt to locate and open the main symbol
983 file. On SVR4 systems, this is the first link map entry. If its
984 name is here, we can open it. Useful when attaching to a process
985 without first loading its symbol file.
987 If FROM_TTYP dereferences to a non-zero integer, allow messages to
988 be printed. This parameter is a pointer rather than an int because
989 open_symbol_file_object() is called via catch_errors() and
990 catch_errors() requires a pointer argument. */
993 open_symbol_file_object (void *from_ttyp
)
995 CORE_ADDR lm
, l_name
;
998 int from_tty
= *(int *)from_ttyp
;
999 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
1000 struct type
*ptr_type
= builtin_type (target_gdbarch
)->builtin_data_ptr
;
1001 int l_name_size
= TYPE_LENGTH (ptr_type
);
1002 gdb_byte
*l_name_buf
= xmalloc (l_name_size
);
1003 struct cleanup
*cleanups
= make_cleanup (xfree
, l_name_buf
);
1004 struct svr4_info
*info
= get_svr4_info ();
1006 if (symfile_objfile
)
1007 if (!query (_("Attempt to reload symbols from process? ")))
1010 /* Always locate the debug struct, in case it has moved. */
1011 info
->debug_base
= 0;
1012 if (locate_base (info
) == 0)
1013 return 0; /* failed somehow... */
1015 /* First link map member should be the executable. */
1016 lm
= solib_svr4_r_map (info
);
1018 return 0; /* failed somehow... */
1020 /* Read address of name from target memory to GDB. */
1021 read_memory (lm
+ lmo
->l_name_offset
, l_name_buf
, l_name_size
);
1023 /* Convert the address to host format. */
1024 l_name
= extract_typed_address (l_name_buf
, ptr_type
);
1026 /* Free l_name_buf. */
1027 do_cleanups (cleanups
);
1030 return 0; /* No filename. */
1032 /* Now fetch the filename from target memory. */
1033 target_read_string (l_name
, &filename
, SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1034 make_cleanup (xfree
, filename
);
1038 warning (_("failed to read exec filename from attached file: %s"),
1039 safe_strerror (errcode
));
1043 /* Have a pathname: read the symbol file. */
1044 symbol_file_add_main (filename
, from_tty
);
1049 /* If no shared library information is available from the dynamic
1050 linker, build a fallback list from other sources. */
1052 static struct so_list
*
1053 svr4_default_sos (void)
1055 struct svr4_info
*info
= get_svr4_info ();
1057 struct so_list
*head
= NULL
;
1058 struct so_list
**link_ptr
= &head
;
1060 if (info
->debug_loader_offset_p
)
1062 struct so_list
*new = XZALLOC (struct so_list
);
1064 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1066 /* Nothing will ever check the cached copy of the link
1067 map if we set l_addr. */
1068 new->lm_info
->l_addr
= info
->debug_loader_offset
;
1069 new->lm_info
->lm_addr
= 0;
1070 new->lm_info
->lm
= NULL
;
1072 strncpy (new->so_name
, info
->debug_loader_name
,
1073 SO_NAME_MAX_PATH_SIZE
- 1);
1074 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1075 strcpy (new->so_original_name
, new->so_name
);
1078 link_ptr
= &new->next
;
1086 current_sos -- build a list of currently loaded shared objects
1090 struct so_list *current_sos ()
1094 Build a list of `struct so_list' objects describing the shared
1095 objects currently loaded in the inferior. This list does not
1096 include an entry for the main executable file.
1098 Note that we only gather information directly available from the
1099 inferior --- we don't examine any of the shared library files
1100 themselves. The declaration of `struct so_list' says which fields
1101 we provide values for. */
1103 static struct so_list
*
1104 svr4_current_sos (void)
1107 struct so_list
*head
= 0;
1108 struct so_list
**link_ptr
= &head
;
1109 CORE_ADDR ldsomap
= 0;
1110 struct svr4_info
*info
;
1112 info
= get_svr4_info ();
1114 /* Always locate the debug struct, in case it has moved. */
1115 info
->debug_base
= 0;
1118 /* If we can't find the dynamic linker's base structure, this
1119 must not be a dynamically linked executable. Hmm. */
1120 if (! info
->debug_base
)
1121 return svr4_default_sos ();
1123 /* Walk the inferior's link map list, and build our list of
1124 `struct so_list' nodes. */
1125 lm
= solib_svr4_r_map (info
);
1129 struct link_map_offsets
*lmo
= svr4_fetch_link_map_offsets ();
1130 struct so_list
*new = XZALLOC (struct so_list
);
1131 struct cleanup
*old_chain
= make_cleanup (xfree
, new);
1133 new->lm_info
= xmalloc (sizeof (struct lm_info
));
1134 make_cleanup (xfree
, new->lm_info
);
1136 new->lm_info
->l_addr
= (CORE_ADDR
)-1;
1137 new->lm_info
->lm_addr
= lm
;
1138 new->lm_info
->lm
= xzalloc (lmo
->link_map_size
);
1139 make_cleanup (xfree
, new->lm_info
->lm
);
1141 read_memory (lm
, new->lm_info
->lm
, lmo
->link_map_size
);
1145 /* For SVR4 versions, the first entry in the link map is for the
1146 inferior executable, so we must ignore it. For some versions of
1147 SVR4, it has no name. For others (Solaris 2.3 for example), it
1148 does have a name, so we can no longer use a missing name to
1149 decide when to ignore it. */
1150 if (IGNORE_FIRST_LINK_MAP_ENTRY (new) && ldsomap
== 0)
1152 info
->main_lm_addr
= new->lm_info
->lm_addr
;
1160 /* Extract this shared object's name. */
1161 target_read_string (LM_NAME (new), &buffer
,
1162 SO_NAME_MAX_PATH_SIZE
- 1, &errcode
);
1164 warning (_("Can't read pathname for load map: %s."),
1165 safe_strerror (errcode
));
1168 strncpy (new->so_name
, buffer
, SO_NAME_MAX_PATH_SIZE
- 1);
1169 new->so_name
[SO_NAME_MAX_PATH_SIZE
- 1] = '\0';
1170 strcpy (new->so_original_name
, new->so_name
);
1174 /* If this entry has no name, or its name matches the name
1175 for the main executable, don't include it in the list. */
1176 if (! new->so_name
[0]
1177 || match_main (new->so_name
))
1183 link_ptr
= &new->next
;
1187 /* On Solaris, the dynamic linker is not in the normal list of
1188 shared objects, so make sure we pick it up too. Having
1189 symbol information for the dynamic linker is quite crucial
1190 for skipping dynamic linker resolver code. */
1191 if (lm
== 0 && ldsomap
== 0)
1192 lm
= ldsomap
= solib_svr4_r_ldsomap (info
);
1194 discard_cleanups (old_chain
);
1198 return svr4_default_sos ();
1203 /* Get the address of the link_map for a given OBJFILE. */
1206 svr4_fetch_objfile_link_map (struct objfile
*objfile
)
1209 struct svr4_info
*info
= get_svr4_info ();
1211 /* Cause svr4_current_sos() to be run if it hasn't been already. */
1212 if (info
->main_lm_addr
== 0)
1213 solib_add (NULL
, 0, ¤t_target
, auto_solib_add
);
1215 /* svr4_current_sos() will set main_lm_addr for the main executable. */
1216 if (objfile
== symfile_objfile
)
1217 return info
->main_lm_addr
;
1219 /* The other link map addresses may be found by examining the list
1220 of shared libraries. */
1221 for (so
= master_so_list (); so
; so
= so
->next
)
1222 if (so
->objfile
== objfile
)
1223 return so
->lm_info
->lm_addr
;
1229 /* On some systems, the only way to recognize the link map entry for
1230 the main executable file is by looking at its name. Return
1231 non-zero iff SONAME matches one of the known main executable names. */
1234 match_main (char *soname
)
1238 for (mainp
= main_name_list
; *mainp
!= NULL
; mainp
++)
1240 if (strcmp (soname
, *mainp
) == 0)
1247 /* Return 1 if PC lies in the dynamic symbol resolution code of the
1248 SVR4 run time loader. */
1251 svr4_in_dynsym_resolve_code (CORE_ADDR pc
)
1253 struct svr4_info
*info
= get_svr4_info ();
1255 return ((pc
>= info
->interp_text_sect_low
1256 && pc
< info
->interp_text_sect_high
)
1257 || (pc
>= info
->interp_plt_sect_low
1258 && pc
< info
->interp_plt_sect_high
)
1259 || in_plt_section (pc
, NULL
));
1262 /* Given an executable's ABFD and target, compute the entry-point
1266 exec_entry_point (struct bfd
*abfd
, struct target_ops
*targ
)
1268 /* KevinB wrote ... for most targets, the address returned by
1269 bfd_get_start_address() is the entry point for the start
1270 function. But, for some targets, bfd_get_start_address() returns
1271 the address of a function descriptor from which the entry point
1272 address may be extracted. This address is extracted by
1273 gdbarch_convert_from_func_ptr_addr(). The method
1274 gdbarch_convert_from_func_ptr_addr() is the merely the identify
1275 function for targets which don't use function descriptors. */
1276 return gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1277 bfd_get_start_address (abfd
),
1285 enable_break -- arrange for dynamic linker to hit breakpoint
1289 int enable_break (void)
1293 Both the SunOS and the SVR4 dynamic linkers have, as part of their
1294 debugger interface, support for arranging for the inferior to hit
1295 a breakpoint after mapping in the shared libraries. This function
1296 enables that breakpoint.
1298 For SunOS, there is a special flag location (in_debugger) which we
1299 set to 1. When the dynamic linker sees this flag set, it will set
1300 a breakpoint at a location known only to itself, after saving the
1301 original contents of that place and the breakpoint address itself,
1302 in it's own internal structures. When we resume the inferior, it
1303 will eventually take a SIGTRAP when it runs into the breakpoint.
1304 We handle this (in a different place) by restoring the contents of
1305 the breakpointed location (which is only known after it stops),
1306 chasing around to locate the shared libraries that have been
1307 loaded, then resuming.
1309 For SVR4, the debugger interface structure contains a member (r_brk)
1310 which is statically initialized at the time the shared library is
1311 built, to the offset of a function (_r_debug_state) which is guaran-
1312 teed to be called once before mapping in a library, and again when
1313 the mapping is complete. At the time we are examining this member,
1314 it contains only the unrelocated offset of the function, so we have
1315 to do our own relocation. Later, when the dynamic linker actually
1316 runs, it relocates r_brk to be the actual address of _r_debug_state().
1318 The debugger interface structure also contains an enumeration which
1319 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
1320 depending upon whether or not the library is being mapped or unmapped,
1321 and then set to RT_CONSISTENT after the library is mapped/unmapped.
1325 enable_break (struct svr4_info
*info
, int from_tty
)
1327 struct minimal_symbol
*msymbol
;
1329 asection
*interp_sect
;
1330 gdb_byte
*interp_name
;
1333 info
->interp_text_sect_low
= info
->interp_text_sect_high
= 0;
1334 info
->interp_plt_sect_low
= info
->interp_plt_sect_high
= 0;
1336 /* If we already have a shared library list in the target, and
1337 r_debug contains r_brk, set the breakpoint there - this should
1338 mean r_brk has already been relocated. Assume the dynamic linker
1339 is the object containing r_brk. */
1341 solib_add (NULL
, from_tty
, ¤t_target
, auto_solib_add
);
1343 if (info
->debug_base
&& solib_svr4_r_map (info
) != 0)
1344 sym_addr
= solib_svr4_r_brk (info
);
1348 struct obj_section
*os
;
1350 sym_addr
= gdbarch_addr_bits_remove
1351 (target_gdbarch
, gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1355 /* On at least some versions of Solaris there's a dynamic relocation
1356 on _r_debug.r_brk and SYM_ADDR may not be relocated yet, e.g., if
1357 we get control before the dynamic linker has self-relocated.
1358 Check if SYM_ADDR is in a known section, if it is assume we can
1359 trust its value. This is just a heuristic though, it could go away
1360 or be replaced if it's getting in the way.
1362 On ARM we need to know whether the ISA of rtld_db_dlactivity (or
1363 however it's spelled in your particular system) is ARM or Thumb.
1364 That knowledge is encoded in the address, if it's Thumb the low bit
1365 is 1. However, we've stripped that info above and it's not clear
1366 what all the consequences are of passing a non-addr_bits_remove'd
1367 address to create_solib_event_breakpoint. The call to
1368 find_pc_section verifies we know about the address and have some
1369 hope of computing the right kind of breakpoint to use (via
1370 symbol info). It does mean that GDB needs to be pointed at a
1371 non-stripped version of the dynamic linker in order to obtain
1372 information it already knows about. Sigh. */
1374 os
= find_pc_section (sym_addr
);
1377 /* Record the relocated start and end address of the dynamic linker
1378 text and plt section for svr4_in_dynsym_resolve_code. */
1380 CORE_ADDR load_addr
;
1382 tmp_bfd
= os
->objfile
->obfd
;
1383 load_addr
= ANOFFSET (os
->objfile
->section_offsets
,
1384 os
->objfile
->sect_index_text
);
1386 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1389 info
->interp_text_sect_low
=
1390 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1391 info
->interp_text_sect_high
=
1392 info
->interp_text_sect_low
1393 + bfd_section_size (tmp_bfd
, interp_sect
);
1395 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1398 info
->interp_plt_sect_low
=
1399 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1400 info
->interp_plt_sect_high
=
1401 info
->interp_plt_sect_low
1402 + bfd_section_size (tmp_bfd
, interp_sect
);
1405 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1410 /* Find the program interpreter; if not found, warn the user and drop
1411 into the old breakpoint at symbol code. */
1412 interp_name
= find_program_interpreter ();
1415 CORE_ADDR load_addr
= 0;
1416 int load_addr_found
= 0;
1417 int loader_found_in_list
= 0;
1419 bfd
*tmp_bfd
= NULL
;
1420 struct target_ops
*tmp_bfd_target
;
1421 volatile struct gdb_exception ex
;
1425 /* Now we need to figure out where the dynamic linker was
1426 loaded so that we can load its symbols and place a breakpoint
1427 in the dynamic linker itself.
1429 This address is stored on the stack. However, I've been unable
1430 to find any magic formula to find it for Solaris (appears to
1431 be trivial on GNU/Linux). Therefore, we have to try an alternate
1432 mechanism to find the dynamic linker's base address. */
1434 TRY_CATCH (ex
, RETURN_MASK_ALL
)
1436 tmp_bfd
= solib_bfd_open (interp_name
);
1438 if (tmp_bfd
== NULL
)
1439 goto bkpt_at_symbol
;
1441 /* Now convert the TMP_BFD into a target. That way target, as
1442 well as BFD operations can be used. Note that closing the
1443 target will also close the underlying bfd. */
1444 tmp_bfd_target
= target_bfd_reopen (tmp_bfd
);
1446 /* On a running target, we can get the dynamic linker's base
1447 address from the shared library table. */
1448 so
= master_so_list ();
1451 if (svr4_same_1 (interp_name
, so
->so_original_name
))
1453 load_addr_found
= 1;
1454 loader_found_in_list
= 1;
1455 load_addr
= LM_ADDR_CHECK (so
, tmp_bfd
);
1461 /* If we were not able to find the base address of the loader
1462 from our so_list, then try using the AT_BASE auxilliary entry. */
1463 if (!load_addr_found
)
1464 if (target_auxv_search (¤t_target
, AT_BASE
, &load_addr
) > 0)
1466 int addr_bit
= gdbarch_addr_bit (target_gdbarch
);
1468 /* Ensure LOAD_ADDR has proper sign in its possible upper bits so
1469 that `+ load_addr' will overflow CORE_ADDR width not creating
1470 invalid addresses like 0x101234567 for 32bit inferiors on 64bit
1473 if (addr_bit
< (sizeof (CORE_ADDR
) * HOST_CHAR_BIT
))
1475 CORE_ADDR space_size
= (CORE_ADDR
) 1 << addr_bit
;
1476 CORE_ADDR tmp_entry_point
= exec_entry_point (tmp_bfd
,
1479 gdb_assert (load_addr
< space_size
);
1481 /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked
1482 64bit ld.so with 32bit executable, it should not happen. */
1484 if (tmp_entry_point
< space_size
1485 && tmp_entry_point
+ load_addr
>= space_size
)
1486 load_addr
-= space_size
;
1489 load_addr_found
= 1;
1492 /* Otherwise we find the dynamic linker's base address by examining
1493 the current pc (which should point at the entry point for the
1494 dynamic linker) and subtracting the offset of the entry point.
1496 This is more fragile than the previous approaches, but is a good
1497 fallback method because it has actually been working well in
1499 if (!load_addr_found
)
1501 struct regcache
*regcache
1502 = get_thread_arch_regcache (inferior_ptid
, target_gdbarch
);
1503 load_addr
= (regcache_read_pc (regcache
)
1504 - exec_entry_point (tmp_bfd
, tmp_bfd_target
));
1507 if (!loader_found_in_list
)
1509 info
->debug_loader_name
= xstrdup (interp_name
);
1510 info
->debug_loader_offset_p
= 1;
1511 info
->debug_loader_offset
= load_addr
;
1512 solib_add (NULL
, from_tty
, ¤t_target
, auto_solib_add
);
1515 /* Record the relocated start and end address of the dynamic linker
1516 text and plt section for svr4_in_dynsym_resolve_code. */
1517 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".text");
1520 info
->interp_text_sect_low
=
1521 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1522 info
->interp_text_sect_high
=
1523 info
->interp_text_sect_low
1524 + bfd_section_size (tmp_bfd
, interp_sect
);
1526 interp_sect
= bfd_get_section_by_name (tmp_bfd
, ".plt");
1529 info
->interp_plt_sect_low
=
1530 bfd_section_vma (tmp_bfd
, interp_sect
) + load_addr
;
1531 info
->interp_plt_sect_high
=
1532 info
->interp_plt_sect_low
1533 + bfd_section_size (tmp_bfd
, interp_sect
);
1536 /* Now try to set a breakpoint in the dynamic linker. */
1537 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1539 sym_addr
= bfd_lookup_symbol (tmp_bfd
, *bkpt_namep
);
1545 /* Convert 'sym_addr' from a function pointer to an address.
1546 Because we pass tmp_bfd_target instead of the current
1547 target, this will always produce an unrelocated value. */
1548 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1552 /* We're done with both the temporary bfd and target. Remember,
1553 closing the target closes the underlying bfd. */
1554 target_close (tmp_bfd_target
, 0);
1558 create_solib_event_breakpoint (target_gdbarch
, load_addr
+ sym_addr
);
1559 xfree (interp_name
);
1563 /* For whatever reason we couldn't set a breakpoint in the dynamic
1564 linker. Warn and drop into the old code. */
1566 xfree (interp_name
);
1567 warning (_("Unable to find dynamic linker breakpoint function.\n"
1568 "GDB will be unable to debug shared library initializers\n"
1569 "and track explicitly loaded dynamic code."));
1572 /* Scan through the lists of symbols, trying to look up the symbol and
1573 set a breakpoint there. Terminate loop when we/if we succeed. */
1575 for (bkpt_namep
= solib_break_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1577 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1578 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1580 sym_addr
= SYMBOL_VALUE_ADDRESS (msymbol
);
1581 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1584 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1589 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1591 msymbol
= lookup_minimal_symbol (*bkpt_namep
, NULL
, symfile_objfile
);
1592 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1594 sym_addr
= SYMBOL_VALUE_ADDRESS (msymbol
);
1595 sym_addr
= gdbarch_convert_from_func_ptr_addr (target_gdbarch
,
1598 create_solib_event_breakpoint (target_gdbarch
, sym_addr
);
1609 special_symbol_handling -- additional shared library symbol handling
1613 void special_symbol_handling ()
1617 Once the symbols from a shared object have been loaded in the usual
1618 way, we are called to do any system specific symbol handling that
1621 For SunOS4, this consisted of grunging around in the dynamic
1622 linkers structures to find symbol definitions for "common" symbols
1623 and adding them to the minimal symbol table for the runtime common
1626 However, for SVR4, there's nothing to do.
1631 svr4_special_symbol_handling (void)
1633 svr4_relocate_main_executable ();
1636 /* Read the ELF program headers from ABFD. Return the contents and
1637 set *PHDRS_SIZE to the size of the program headers. */
1640 read_program_headers_from_bfd (bfd
*abfd
, int *phdrs_size
)
1642 Elf_Internal_Ehdr
*ehdr
;
1645 ehdr
= elf_elfheader (abfd
);
1647 *phdrs_size
= ehdr
->e_phnum
* ehdr
->e_phentsize
;
1648 if (*phdrs_size
== 0)
1651 buf
= xmalloc (*phdrs_size
);
1652 if (bfd_seek (abfd
, ehdr
->e_phoff
, SEEK_SET
) != 0
1653 || bfd_bread (buf
, *phdrs_size
, abfd
) != *phdrs_size
)
1662 /* We relocate all of the sections by the same amount. This
1663 behavior is mandated by recent editions of the System V ABI.
1664 According to the System V Application Binary Interface,
1665 Edition 4.1, page 5-5:
1667 ... Though the system chooses virtual addresses for
1668 individual processes, it maintains the segments' relative
1669 positions. Because position-independent code uses relative
1670 addressesing between segments, the difference between
1671 virtual addresses in memory must match the difference
1672 between virtual addresses in the file. The difference
1673 between the virtual address of any segment in memory and
1674 the corresponding virtual address in the file is thus a
1675 single constant value for any one executable or shared
1676 object in a given process. This difference is the base
1677 address. One use of the base address is to relocate the
1678 memory image of the program during dynamic linking.
1680 The same language also appears in Edition 4.0 of the System V
1681 ABI and is left unspecified in some of the earlier editions.
1683 Decide if the objfile needs to be relocated. As indicated above, we will
1684 only be here when execution is stopped. But during attachment PC can be at
1685 arbitrary address therefore regcache_read_pc can be misleading (contrary to
1686 the auxv AT_ENTRY value). Moreover for executable with interpreter section
1687 regcache_read_pc would point to the interpreter and not the main executable.
1689 So, to summarize, relocations are necessary when the start address obtained
1690 from the executable is different from the address in auxv AT_ENTRY entry.
1692 [ The astute reader will note that we also test to make sure that
1693 the executable in question has the DYNAMIC flag set. It is my
1694 opinion that this test is unnecessary (undesirable even). It
1695 was added to avoid inadvertent relocation of an executable
1696 whose e_type member in the ELF header is not ET_DYN. There may
1697 be a time in the future when it is desirable to do relocations
1698 on other types of files as well in which case this condition
1699 should either be removed or modified to accomodate the new file
1700 type. - Kevin, Nov 2000. ] */
1703 svr4_exec_displacement (void)
1705 /* ENTRY_POINT is a possible function descriptor - before
1706 a call to gdbarch_convert_from_func_ptr_addr. */
1707 CORE_ADDR entry_point
, displacement
;
1709 if (exec_bfd
== NULL
)
1712 /* Therefore for ELF it is ET_EXEC and not ET_DYN. Both shared libraries
1713 being executed themselves and PIE (Position Independent Executable)
1714 executables are ET_DYN. */
1716 if ((bfd_get_file_flags (exec_bfd
) & DYNAMIC
) == 0)
1719 if (target_auxv_search (¤t_target
, AT_ENTRY
, &entry_point
) <= 0)
1722 displacement
= entry_point
- bfd_get_start_address (exec_bfd
);
1724 /* Verify the DISPLACEMENT candidate complies with the required page
1725 alignment. It is cheaper than the program headers comparison below. */
1727 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
1729 const struct elf_backend_data
*elf
= get_elf_backend_data (exec_bfd
);
1731 /* p_align of PT_LOAD segments does not specify any alignment but
1732 only congruency of addresses:
1733 p_offset % p_align == p_vaddr % p_align
1734 Kernel is free to load the executable with lower alignment. */
1736 if ((displacement
& (elf
->minpagesize
- 1)) != 0)
1740 /* Verify that the auxilliary vector describes the same file as exec_bfd, by
1741 comparing their program headers. If the program headers in the auxilliary
1742 vector do not match the program headers in the executable, then we are
1743 looking at a different file than the one used by the kernel - for
1744 instance, "gdb program" connected to "gdbserver :PORT ld.so program". */
1746 if (bfd_get_flavour (exec_bfd
) == bfd_target_elf_flavour
)
1748 /* Be optimistic and clear OK only if GDB was able to verify the headers
1749 really do not match. */
1750 int phdrs_size
, phdrs2_size
, ok
= 1;
1751 gdb_byte
*buf
, *buf2
;
1753 buf
= read_program_header (-1, &phdrs_size
, NULL
);
1754 buf2
= read_program_headers_from_bfd (exec_bfd
, &phdrs2_size
);
1755 if (buf
!= NULL
&& buf2
!= NULL
1756 && (phdrs_size
!= phdrs2_size
1757 || memcmp (buf
, buf2
, phdrs_size
) != 0))
1767 return displacement
;
1770 /* Relocate the main executable. This function should be called upon
1771 stopping the inferior process at the entry point to the program.
1772 The entry point from BFD is compared to the AT_ENTRY of AUXV and if they are
1773 different, the main executable is relocated by the proper amount. */
1776 svr4_relocate_main_executable (void)
1778 CORE_ADDR displacement
= svr4_exec_displacement ();
1780 /* Even if DISPLACEMENT is 0 still try to relocate it as this is a new
1781 difference of in-memory vs. in-file addresses and we could already
1782 relocate the executable at this function to improper address before. */
1784 if (symfile_objfile
)
1786 struct section_offsets
*new_offsets
;
1789 new_offsets
= alloca (symfile_objfile
->num_sections
1790 * sizeof (*new_offsets
));
1792 for (i
= 0; i
< symfile_objfile
->num_sections
; i
++)
1793 new_offsets
->offsets
[i
] = displacement
;
1795 objfile_relocate (symfile_objfile
, new_offsets
);
1801 for (asect
= exec_bfd
->sections
; asect
!= NULL
; asect
= asect
->next
)
1802 exec_set_section_address (bfd_get_filename (exec_bfd
), asect
->index
,
1803 (bfd_section_vma (exec_bfd
, asect
)
1812 svr4_solib_create_inferior_hook -- shared library startup support
1816 void svr4_solib_create_inferior_hook (int from_tty)
1820 When gdb starts up the inferior, it nurses it along (through the
1821 shell) until it is ready to execute it's first instruction. At this
1822 point, this function gets called via expansion of the macro
1823 SOLIB_CREATE_INFERIOR_HOOK.
1825 For SunOS executables, this first instruction is typically the
1826 one at "_start", or a similar text label, regardless of whether
1827 the executable is statically or dynamically linked. The runtime
1828 startup code takes care of dynamically linking in any shared
1829 libraries, once gdb allows the inferior to continue.
1831 For SVR4 executables, this first instruction is either the first
1832 instruction in the dynamic linker (for dynamically linked
1833 executables) or the instruction at "start" for statically linked
1834 executables. For dynamically linked executables, the system
1835 first exec's /lib/libc.so.N, which contains the dynamic linker,
1836 and starts it running. The dynamic linker maps in any needed
1837 shared libraries, maps in the actual user executable, and then
1838 jumps to "start" in the user executable.
1840 For both SunOS shared libraries, and SVR4 shared libraries, we
1841 can arrange to cooperate with the dynamic linker to discover the
1842 names of shared libraries that are dynamically linked, and the
1843 base addresses to which they are linked.
1845 This function is responsible for discovering those names and
1846 addresses, and saving sufficient information about them to allow
1847 their symbols to be read at a later time.
1851 Between enable_break() and disable_break(), this code does not
1852 properly handle hitting breakpoints which the user might have
1853 set in the startup code or in the dynamic linker itself. Proper
1854 handling will probably have to wait until the implementation is
1855 changed to use the "breakpoint handler function" method.
1857 Also, what if child has exit()ed? Must exit loop somehow.
1861 svr4_solib_create_inferior_hook (int from_tty
)
1863 struct inferior
*inf
;
1864 struct thread_info
*tp
;
1865 struct svr4_info
*info
;
1867 info
= get_svr4_info ();
1869 /* Relocate the main executable if necessary. */
1870 if (current_inferior ()->attach_flag
== 0)
1871 svr4_relocate_main_executable ();
1873 if (!svr4_have_link_map_offsets ())
1876 if (!enable_break (info
, from_tty
))
1879 #if defined(_SCO_DS)
1880 /* SCO needs the loop below, other systems should be using the
1881 special shared library breakpoints and the shared library breakpoint
1884 Now run the target. It will eventually hit the breakpoint, at
1885 which point all of the libraries will have been mapped in and we
1886 can go groveling around in the dynamic linker structures to find
1887 out what we need to know about them. */
1889 inf
= current_inferior ();
1890 tp
= inferior_thread ();
1892 clear_proceed_status ();
1893 inf
->stop_soon
= STOP_QUIETLY
;
1894 tp
->stop_signal
= TARGET_SIGNAL_0
;
1897 target_resume (pid_to_ptid (-1), 0, tp
->stop_signal
);
1898 wait_for_inferior (0);
1900 while (tp
->stop_signal
!= TARGET_SIGNAL_TRAP
);
1901 inf
->stop_soon
= NO_STOP_QUIETLY
;
1902 #endif /* defined(_SCO_DS) */
1906 svr4_clear_solib (void)
1908 struct svr4_info
*info
;
1910 info
= get_svr4_info ();
1911 info
->debug_base
= 0;
1912 info
->debug_loader_offset_p
= 0;
1913 info
->debug_loader_offset
= 0;
1914 xfree (info
->debug_loader_name
);
1915 info
->debug_loader_name
= NULL
;
1919 svr4_free_so (struct so_list
*so
)
1921 xfree (so
->lm_info
->lm
);
1922 xfree (so
->lm_info
);
1926 /* Clear any bits of ADDR that wouldn't fit in a target-format
1927 data pointer. "Data pointer" here refers to whatever sort of
1928 address the dynamic linker uses to manage its sections. At the
1929 moment, we don't support shared libraries on any processors where
1930 code and data pointers are different sizes.
1932 This isn't really the right solution. What we really need here is
1933 a way to do arithmetic on CORE_ADDR values that respects the
1934 natural pointer/address correspondence. (For example, on the MIPS,
1935 converting a 32-bit pointer to a 64-bit CORE_ADDR requires you to
1936 sign-extend the value. There, simply truncating the bits above
1937 gdbarch_ptr_bit, as we do below, is no good.) This should probably
1938 be a new gdbarch method or something. */
1940 svr4_truncate_ptr (CORE_ADDR addr
)
1942 if (gdbarch_ptr_bit (target_gdbarch
) == sizeof (CORE_ADDR
) * 8)
1943 /* We don't need to truncate anything, and the bit twiddling below
1944 will fail due to overflow problems. */
1947 return addr
& (((CORE_ADDR
) 1 << gdbarch_ptr_bit (target_gdbarch
)) - 1);
1952 svr4_relocate_section_addresses (struct so_list
*so
,
1953 struct target_section
*sec
)
1955 sec
->addr
= svr4_truncate_ptr (sec
->addr
+ LM_ADDR_CHECK (so
,
1957 sec
->endaddr
= svr4_truncate_ptr (sec
->endaddr
+ LM_ADDR_CHECK (so
,
1962 /* Architecture-specific operations. */
1964 /* Per-architecture data key. */
1965 static struct gdbarch_data
*solib_svr4_data
;
1967 struct solib_svr4_ops
1969 /* Return a description of the layout of `struct link_map'. */
1970 struct link_map_offsets
*(*fetch_link_map_offsets
)(void);
1973 /* Return a default for the architecture-specific operations. */
1976 solib_svr4_init (struct obstack
*obstack
)
1978 struct solib_svr4_ops
*ops
;
1980 ops
= OBSTACK_ZALLOC (obstack
, struct solib_svr4_ops
);
1981 ops
->fetch_link_map_offsets
= NULL
;
1985 /* Set the architecture-specific `struct link_map_offsets' fetcher for
1986 GDBARCH to FLMO. Also, install SVR4 solib_ops into GDBARCH. */
1989 set_solib_svr4_fetch_link_map_offsets (struct gdbarch
*gdbarch
,
1990 struct link_map_offsets
*(*flmo
) (void))
1992 struct solib_svr4_ops
*ops
= gdbarch_data (gdbarch
, solib_svr4_data
);
1994 ops
->fetch_link_map_offsets
= flmo
;
1996 set_solib_ops (gdbarch
, &svr4_so_ops
);
1999 /* Fetch a link_map_offsets structure using the architecture-specific
2000 `struct link_map_offsets' fetcher. */
2002 static struct link_map_offsets
*
2003 svr4_fetch_link_map_offsets (void)
2005 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
2007 gdb_assert (ops
->fetch_link_map_offsets
);
2008 return ops
->fetch_link_map_offsets ();
2011 /* Return 1 if a link map offset fetcher has been defined, 0 otherwise. */
2014 svr4_have_link_map_offsets (void)
2016 struct solib_svr4_ops
*ops
= gdbarch_data (target_gdbarch
, solib_svr4_data
);
2017 return (ops
->fetch_link_map_offsets
!= NULL
);
2021 /* Most OS'es that have SVR4-style ELF dynamic libraries define a
2022 `struct r_debug' and a `struct link_map' that are binary compatible
2023 with the origional SVR4 implementation. */
2025 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
2026 for an ILP32 SVR4 system. */
2028 struct link_map_offsets
*
2029 svr4_ilp32_fetch_link_map_offsets (void)
2031 static struct link_map_offsets lmo
;
2032 static struct link_map_offsets
*lmp
= NULL
;
2038 lmo
.r_version_offset
= 0;
2039 lmo
.r_version_size
= 4;
2040 lmo
.r_map_offset
= 4;
2041 lmo
.r_brk_offset
= 8;
2042 lmo
.r_ldsomap_offset
= 20;
2044 /* Everything we need is in the first 20 bytes. */
2045 lmo
.link_map_size
= 20;
2046 lmo
.l_addr_offset
= 0;
2047 lmo
.l_name_offset
= 4;
2048 lmo
.l_ld_offset
= 8;
2049 lmo
.l_next_offset
= 12;
2050 lmo
.l_prev_offset
= 16;
2056 /* Fetch (and possibly build) an appropriate `struct link_map_offsets'
2057 for an LP64 SVR4 system. */
2059 struct link_map_offsets
*
2060 svr4_lp64_fetch_link_map_offsets (void)
2062 static struct link_map_offsets lmo
;
2063 static struct link_map_offsets
*lmp
= NULL
;
2069 lmo
.r_version_offset
= 0;
2070 lmo
.r_version_size
= 4;
2071 lmo
.r_map_offset
= 8;
2072 lmo
.r_brk_offset
= 16;
2073 lmo
.r_ldsomap_offset
= 40;
2075 /* Everything we need is in the first 40 bytes. */
2076 lmo
.link_map_size
= 40;
2077 lmo
.l_addr_offset
= 0;
2078 lmo
.l_name_offset
= 8;
2079 lmo
.l_ld_offset
= 16;
2080 lmo
.l_next_offset
= 24;
2081 lmo
.l_prev_offset
= 32;
2088 struct target_so_ops svr4_so_ops
;
2090 /* Lookup global symbol for ELF DSOs linked with -Bsymbolic. Those DSOs have a
2091 different rule for symbol lookup. The lookup begins here in the DSO, not in
2092 the main executable. */
2094 static struct symbol
*
2095 elf_lookup_lib_symbol (const struct objfile
*objfile
,
2097 const domain_enum domain
)
2101 if (objfile
== symfile_objfile
)
2105 /* OBJFILE should have been passed as the non-debug one. */
2106 gdb_assert (objfile
->separate_debug_objfile_backlink
== NULL
);
2108 abfd
= objfile
->obfd
;
2111 if (abfd
== NULL
|| scan_dyntag (DT_SYMBOLIC
, abfd
, NULL
) != 1)
2114 return lookup_global_symbol_from_objfile (objfile
, name
, domain
);
2117 extern initialize_file_ftype _initialize_svr4_solib
; /* -Wmissing-prototypes */
2120 _initialize_svr4_solib (void)
2122 solib_svr4_data
= gdbarch_data_register_pre_init (solib_svr4_init
);
2123 solib_svr4_pspace_data
2124 = register_program_space_data_with_cleanup (svr4_pspace_data_cleanup
);
2126 svr4_so_ops
.relocate_section_addresses
= svr4_relocate_section_addresses
;
2127 svr4_so_ops
.free_so
= svr4_free_so
;
2128 svr4_so_ops
.clear_solib
= svr4_clear_solib
;
2129 svr4_so_ops
.solib_create_inferior_hook
= svr4_solib_create_inferior_hook
;
2130 svr4_so_ops
.special_symbol_handling
= svr4_special_symbol_handling
;
2131 svr4_so_ops
.current_sos
= svr4_current_sos
;
2132 svr4_so_ops
.open_symbol_file_object
= open_symbol_file_object
;
2133 svr4_so_ops
.in_dynsym_resolve_code
= svr4_in_dynsym_resolve_code
;
2134 svr4_so_ops
.bfd_open
= solib_bfd_open
;
2135 svr4_so_ops
.lookup_lib_global_symbol
= elf_lookup_lib_symbol
;
2136 svr4_so_ops
.same
= svr4_same
;
2137 svr4_so_ops
.keep_data_in_core
= svr4_keep_data_in_core
;